Because of the complex structure of grader working device, its optimization is a repeated, continuously improved process. A new model has to be set up before each optimization. In order to solve the problem of repeating modeling and improve the product optimization efficiency, a second development system of working device is established. Parametric driving about working device is realized in term of spatial mechanism. At first, the overall design framework of this second development system was established, then customized user interface was completed based on UG/Open API and parametric programs about the working device system were complied based on UG/Open Grip subsequently. The connection among customized user interface, parametric programs and human-computer interaction was realized by using Visual C++, the integrated second development system design of working device was eventually completed. This second development system could not only provide engineers with a rapid design method to shorten the new product development cycle, but solve the problem of repeating modeling during optimization design as well.